1. Field of the Invention
The present invention relates generally to crop harvesting equipment and, more particularly, to pull-type mowers or mower/conditioners in which the front of the header can be adjustably tilted up or down to change the angle of attack of the cutter mechanism on the header.
2. Discussion of Prior Art
It is known to provide harvesting machines having a harvesting header which may be adjustably tilted between a number of harvesting positions. Specifically, mower/conditioners are often provided with a harvesting header having a cutter bed transverse to the path of travel of the machine; the header being adjustable to vary the mowing angle relative to the ground (this is commonly referred to as the "guard angle").
An example of a mower/conditioner having an adjustable harvesting header is disclosed in U.S. Pat. No. 5,272,859 titled MECHANICAL DRIVE CENTER PIVOT MOWER CONDITIONER, which is owned by the assignee of the present invention. The harvesting machine disclosed in the '859 Patent is a pull-type harvester which requires the use of a separate tractor for towing the harvester through the field during use. Further, the '859 harvesting machine utilizes a header which may be adjusted to various guard angles.
The guard angle in that machine is adjusted in response to harvesting conditions. For example, in ideal conditions (i.e., dry climate and free standing crop) the guard angle is preferably set at approximately three degrees. In down crop conditions (wet or matted crop) the guard angle is preferably set at around six degrees. In rocky conditions or in portions of the field having numerous obstructions, such as dirt clods, the guard angle is set at zero degrees (i.e., substantially parallel to the ground). Finally, the guard angle may also be adjusted by the operator to vary the cut crop stubble height.
Contrary to most self-propelled harvesters, the harvesting header of the '859 harvester must be manually adjusted to vary the guard angle. Such adjustment requires the machine operator to stop harvesting operations, disconnect all power to the harvester (mechanical and hydraulic), exit the towing vehicle, adjust the header as necessary and finally resume crop harvesting. Obviously, such a process is bothersome and time-consuming.
Therefore, it would be desirable to have a harvesting machine that provides remote header tilt adjustment, preferably controlled from within the cab of the towing vehicle (i.e., at the tractor seat). Traditional towing vehicles are provided with power sources, such as a power takeoff shaft and pressurized hydraulic fluid, that are controlled from within the tractor seat. Operating components of a harvester may be remotely controlled (from the tractor seat) by coupling these components with one of the towing vehicle power sources. Thus, it would be desirable to remotely control header tilt adjustment by utilizing one of the existing power sources of the towing vehicle.
However, the solution for remotely controlling header tilt is not so simple. Although towing vehicles are furnished with power sources for driving harvester components, the number of these sources is limited. Most often, towing vehicles have a single mechanical power takeoff shaft and two sources of pressurized hydraulic fluid. Unfortunately, this configuration limits the number of harvesting functions which may be controlled from within the vehicle cab.
If a conventional pull-type harvester is already utilizing both of the towing vehicle power sources for functions other than header tilt adjustment (e.g., for mowing the crop, frame elevation and swinging of a pulling tongue), the header tilt may not be remotely controlled and powered by the towing vehicle; unless, of course, the operator manually disconnects a power source from one of the other harvesting functions and reconnects it to the mechanism for adjusting header tilt. In this situation, the machine operator is left with two equally poor options; 1) replace an existing harvesting function with header tilt adjustment, which may eliminate a function essential to harvesting operations; or 2) expend the time necessary to manually switch a power source from one component to another. Thus, it would be further desirable to have a pull-type harvester that uses one of the towing vehicle's power sources for header tilt adjustment, without having to wholly eliminate a harvesting function or manually disconnect and reconnect the harvester's components to the power sources.